Carburetors which are now in general use for internal combustion engines employ conventional venturi type fuel-air ratio control systems which are quite complex in construction and adjustment. This type of system is such that it can be designed for maximum efficiency only within a relatively limited range with the result that efficiency is sacrificed outside such range. Additionally, a supplemental supply of fuel is injected under certain conditions, such as a rapid acceleration from idling position, which further complicates the apparatus involved in the system. The net result of these conventional systems is inefficient combustion which not only affects engine operation but also causes some of the unburned fuel to be discharged through the engine exhaust.
The above deficiencies in the carburetors now in use have long been recognized and various attempts have been made to design carburetors wherein the fuel supply is automatically adjusted to actual air intake regardless of the position of the air flow control means. These prior art carburetors have taken the form of a fuel valve which coacts in one manner or another with an air flow control assembly so that theoretically, any motion of the air flow control assembly also adjusts the flow of fuel accordingly. Additionally, some of these devices have rotated the air flow control assembly and have discharged the fuel into the air stream to enhance the mixture of the fuel with the incoming air. Examples of these prior art carburetors are exemplified by U.S. Pat. Nos. 1,439,573, 1,484,577, 3,265,374 and 3,339,900. Although showing the basic concept of an air flow assembly controlled by engine suction and coacting with a fuel valve, these prior devices have failed to accomplish accurate control of fuel-air mixture for various reasons, such as improper mounting of the air flow control assembly or of the fuel control valve, undesirable location of fuel and air inlets or an ineffective shape of the fuel-air mixing chamber. As a result, none of the prior art carburetors accomplish proper control of the air-fuel mixture throughout all ranges and loads of engine operation.